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745 E65 M62 engine misfire

Hi Guys
Great forum, I didnít know all this stuff was out there!
Can anyone help with this one, please, as getting to the end of my tether with it!
E65, M62 Engine, misfire no. 5 cylinder, producing engine management light and warning to accelerate gently. Had new coils all round, plugs. Had the hydro valve compensators replaced by BMW, clearly a misdiagnosis, as the fault has returned a few weeks later. Swapping coils about prior to replacing all coils seemed to work, for a day or so, then re-occured. No faith in them anymore, and we have fallen out. Iím about to take the case up with BMW UK, but looking for as much ammunition as possible prior to emailing, preferably with any info you guys may have regarding recalls, etc, or any internal bulletins at BMW regarding misfires on this engine.
One BMW service head at one dealer thinks it will be broken valve spring? Another says he reckons it will be worn intermediate levers / eccentric shafts, and has admitted to me off the record that there was a 2005 internal bulletin on said levers / shafts ?
Any suggestions / experience / diagnosis greatly appreciated!
thanks

Re: 745 E65 M62 engine misfire

The car ran very good except for the blue smoke on startup and when the SES light came on due to failed coils/spark plugs which caused rough idle.

Next week my engine with 55,000 miles will be replaced due to flaking of the no.1 cylinder which caused a cracked spark plug and burned coil, low compression, and failure of the no.8 spark plug. Symptoms included blue smoke at startup, oil usage, and SES lights. For those of you that have had engine replacements, please provide advice on what potential problems I should look for or possibly expect. Your wisdom will be greatly appreciated.

You may want to analyze the techís write up which may give you more insight to your problem. Good luck!

Technician write up

For cyc.1 misfire with cutout, cleared fault and test drove and fault came back, swaped out coil with #2 and fault still in #1, pulled spark plug and found spark plug to be corroded. Replaced all spark plugs and fault still in cyl 1, swapped fuel injector with #3 and fault still in 1, pulled #1 spark plug and found to be oil soaked, checked engine vacuum with slack tube and had a major leak, pulled throttle body and found excessive oil in intake, pulled both valve covers and checked for damage on oil seperators which are built into the valve covers and no problem was found, ran compression test and all cylinders pass but 1 was a little low, submitted PUMA case and was instructed to check the eccentric shafts per bulletin, R&R both valve covers again to check shafts and had already been replaced, also checked for sludge build up all looked fine, then performed a cyl leak down test on all cyls and 1 was excessive and could hear a leak when pulling the dip stick out, then checked bank 1 cylinders with a bore-a-scope and found pitting and scaling in #1 cylinder, PUMA responded to replace the engine. After replacement topped of all fluids performed ARS startup procedure and cleared fault memory.

Re: You have an n62 engine

Hi, Guys
Thanks for looking and replying.
bmwtech2003, you say the lever problem only occurs on cold starts?
This is disconcerting if you are right, because the service manager where the car now is, is placing his bets on it being that problem. So I don't want another wasted £2k+ spent on this car! It does have the same problem whether cold or hot started, so are you sure he's going down the wrong path, and are you aware of the internal BMW bulletin relating to the levers and shafts problem, allegedly in 2005?
I shall ask him in any event to relay to me the leakdown and compression results,as you suggest.

Re: You have an n62 engine

The N62 Misfire Problem.
I am working on a 2005 N62 4.0 engine. The entire right bank, that is bank 1-4 is without compression. Zero from 1-4. Someone tried to repair a zero compression problem on cylinder 1. I have checked the cam timing inlet and exhaust with the N62 timing gauges. The intake was ok however the exhaust was miles off. Nevertheless it was adjusted to the correct position. The trouble is doing a leak down test does not reveal much, I can detect no passage of air into either the intake or exhaust track. There is a faint passage of air into the crankcase as you can hear the air escaping when you remove the oil filler cap. The rough running values for the bank 1-4 is out of this world, 16.43, 7.90, 14.75,and 9.56 from 1-4.The engine will run smoothly when accelerated to around 1500 RPM. At that RPM, smooth running values turns to 0.00 on all cylinders. At idle its a mess. I am aware of the Valvetronic, its leavers and shaft and the role that it plays in the induction process. However observing the GT1 I can see the lift at idle speed and at increased speeds as well. Further it is not in limp mode. The codes the GT1 is blowing are misfire codes from 1-4 along with two VANOS codes, one for the inlet unit and one for the exhaust. I will work on the latter two to see if the problem is in those units. I will report my findings. Strange vehicle, and may I say the engineering is very poor for a car costing a bundle.

Re: You have an n62 engine

Update.
Compression on the right bank restored by re adjusting the basic minimum lift position on the eccentric shaft assembly. Now to calibrate the both banks and see the results. The problem is the wearing of the intermediate levers and rocker arms, it is possible for this to happen on just one cylinder as well as all on one bank. The repair is possible but very expensive with the assembly jig costing somewhere around US $4,000. Will keep you posted.